CLINICAL ARTICLE J Neurosurg Spine 28:357–363, 2018 L umbar pedicle screw-rod fxation for interbody fu- sion or supplemental posterior fxation traditionally uses open anatomical landmarks for screw entry points and pedicle cannulation. The evolution of mini- mally invasive spine surgery (MISS) has removed these visible anatomical landmarks and is instead reliant on 2D fuoroscopy for pedicle cannulation and Kirchner wire (K- wire) placement. 6,16 K-wires can break, pull out, or advance during pedicle screw insertion and potentially cause neu- ral, vascular, or visceral injury. 8 A “K-wireless” technique using 2D fuoroscopy has been described. 17 The development of intraoperative 3D fuoroscopy and ABBREVIATIONS ALIF = anterior lumbar interbody fusion; LED = light-emitting diode; LLIF = lateral lumbar interbody fusion; MISS = minimally invasive spine surgery; PLIF = posterior lumbar interbody fusion; tEMG = triggered electromyography; TLIF = transforaminal lumbar interbody fusion. ACCOMPANYING EDITORIAL See pp 355–356. DOI: 10.3171/2017.8.SPINE17747. SUBMITTED May 8, 2017. ACCEPTED July 6, 2017. INCLUDE WHEN CITING Published online January 26, 2018; DOI: 10.3171/2017.7.SPINE17528. Early experience of placing image-guided minimally invasive pedicle screws without K-wires or bone-anchored trackers Gregory M. Malham, MBChB, FRACS, 1 and Rhiannon M. Parker, PhD 2 1 Neuroscience Institute, Epworth Hospital, and 2 Research Department, Greg Malham Neurosurgeon, Melbourne, Victoria, Australia OBJECTIVE Image guidance for spine surgery has been reported to improve the accuracy of pedicle screw placement and reduce revision rates and radiation exposure. Current navigation and robot-assisted techniques for percutaneous screws rely on bone-anchored trackers and Kirchner wires (K-wires). There is a paucity of published data regarding the placement of image-guided percutaneous screws without K-wires. A new skin-adhesive stereotactic patient tracker (SpineMask) eliminates both an invasive bone-anchored tracker and K-wires for pedicle screw placement. This study reports the authors’ early experience with the use of SpineMask for “K-wireless” placement of minimally invasive pedicle screws and makes recommendations for its potential applications in lumbar fusion. METHODS Forty-fve consecutive patients (involving 204 screws inserted) underwent K-wireless lumbar pedicle screw fxation with SpineMask and intraoperative neuromonitoring. Screws were inserted by percutaneous stab or Wiltse inci - sions. If required, decompression with or without interbody fusion was performed using mini-open midline incisions. Multimodality intraoperative neuromonitoring assessing motor and sensory responses with triggered electromyography (tEMG) was performed. Computed tomography scans were obtained 2 days postoperatively to assess screw placement and any cortical breaches. A breach was defned as any violation of a pedicle screw involving the cortical bone of the pedicle. RESULTS Fourteen screws (7%) required intraoperative revision. Screws were removed and repositioned due to a tEMG response < 13 mA, tactile feedback, and 3D fuoroscopic assessment. All screws were revised using the Spine- Mask with the same screw placement technique. The highest proportion of revisions occurred with Wiltse incisions (4/12, 33%) as this caused the greatest degree of SpineMask deformation, followed by a mini midline incision (3/26, 12%). Per- cutaneous screws via a single stab incision resulted in the fewest revisions (7/166, 4%). Postoperative CT demonstrated 7 pedicle screw breaches (3%; 5 lateral, 1 medial, 1 superior), all with percutaneous stab incisions (7/166, 4%). The radiological accuracy of the SpineMask tracker was 97% (197/204 screws). No patients suffered neural injury or required postoperative screw revision. CONCLUSIONS The noninvasive cutaneous SpineMask tracker with 3D image guidance and tEMG monitoring pro- vided high accuracy (97%) for percutaneous pedicle screw placement via stab incisions without K-wires. https://thejns.org/doi/abs/10.3171/2017.7.SPINE17528 KEY WORDS K-wireless; image guidance; navigation; neuromonitoring; pedicle screw; percutaneous; surgical technique J Neurosurg Spine Volume 28 • April 2018 357 ©AANS 2018, except where prohibited by US copyright law Unauthenticated | Downloaded 02/16/23 03:25 PM UTC